This invention relates to the field of vacuum systems and in particular to an airborne particulate removal apparatus having a main flexible conduit in fluid communication with a plurality of flexible secondary conduits rotatably mounted to the primary conduit.
As stated by Parker in U.S. Pat. No. 5,160,292 which issued Nov. 3, 1992 for A Vacuum System for Multiple Work Areas, many industries use equipment which in operation generates atmospheric contaminants, which might be gases or airborne particles. These gases and particles are sometimes a health hazard to the operator, as well as to other employees and the environment in general. This problem is especially acute in industrial operations such as wood-working or painting, where dust and gases that are harmful if inhaled are generated in close proximity to the worker. Additionally, particulates can eventually build up and damage equipment in the work area, and often require regular cleaning of the work area. Government regulations in many instances now strictly regulate the amount of such gases and particles which can be present in or emitted from the work area.
Vacuum systems have been installed to withdraw airborne contaminants generated in such work areas. A single vacuum source is usually provided. A manifold usually communicates between the vacuum source and a number of vacuum conduits, the conduits extending to individual work areas. Vacuum openings in the vacuum conduits are provided at the work areas to permit the withdrawal of air from the work area. The gases and particles in the air are thereby removed, and subsequent filtration or other cleansing operations can be employed downstream to permit subsequent disposal of the contaminants. A hood can be provided in association with each vacuum conduit and vacuum opening to reduce the amount of particles and gases that escape from the work area.
As disclosed in U.S. Pat. No. 6,322,618 which issued Nov. 27, 2001 to Simms et al. for An Adjustable Duct Assembly for Fume and Dust Removal and Filter Cleaner, an adjustable duct assembly for the collection of fumes, dust and the like may include two duct sections connected end-to-end by a duct support system which includes two elongate arms pivotally connected, the arms attached to the adjacent ends of the ducts. Similarly, applicant is aware of U.S. Pat. No. 5,482,505 which issued Jan. 9, 1996 to Hedlund for An Arrangement for Extraction of Harmful Gases from Workplaces in which is disclosed a carrier arm having two arms connected telescopically with each other where the carrier is swivel mounted so that it can be swivelled in a vertical direction between a downward-directed position and an outward-directed for example horizontal position. Similarly also, applicant is aware of U.S. Pat. No. 5,738,148 which issued Apr. 14, 1998 to Coral et al. for a Universal Connector Hose for Joining an Extractor to an Element for Extracting Fumes from a Factory Workplace in which is disclosed a hose having two flexible portions connected respectively to the suction unit and to the fume-conveyor element or hood and a rectilinear portion which is articulated to the suction unit and the hood. Other articulated fume extraction arms of which applicant is aware are described in the following U.S. Pat. Nos. 4,540,202; 5,427,569; 5,527,217; 5,536,206; 4,860,644; and 5,336,130.
What is neither taught nor suggested in the prior art, and what is one of the objects of the present invention to provide, is a constant diameter modular ducting having a cable suspension system and which is, when compared to the prior art, easy to erect, and which may be a low static compressed air driven fan system providing multiplexing capabilities of, for example, five hose airstreams to one primary hub having a single low pressure source such as a central exhaust fan. The flex hose design of the present invention provides suction outlets which may optimize fume extraction with minimal repositioning and which, at the other end of the flex hoses, are provided with hose-to-main duct fittings which minimize static pressure drop and equalize flow in multiple flex hose arms.
In one embodiment of the present invention, a main or primary flexible duct has alternating flexible sections and rigid sections, providing a duct of substantially constant sixteen inch diameter. Prefabricated hose connection pieces provide for rapid assembly using releasable hose clamps to modularly secure the modular sections of the primary ducting to each other. Advantageously, the primary duct is tubular. The ducting provides maximum versatility in conforming to a round, square or rectangular work space or may be extended in a straight line. Equal exhaust flow from each of a plurality of flexible secondary hoses, that is, the hose arms or legs, which may be four inch diameter hoses, branching from the primary duct is promoted by static pressure optimization of the flow from the secondary hoses through flow optimizing fittings, which may in a preferred embodiment be diffuser fittings having a four to six inch diameter feeding into a sixteen inch primary duct, where the diffuser fittings incline the flow from the secondary hoses in the direction of flow through the primary ducting.
A fan housing has external loops, which permit a cable attachment to the nearby first wall of a building. At the opposite end of the run of primary ducting, an end cap has a bar, which extends outwardly of the cap to allow a cable yoke to be attached. A tensioning/supporting cable is attached to the yoke, passes around pulleys attached to the opposite second end of the building and returns to an anchoring point at the first wall. A tensioning device is provided near the second wall for applying or relieving tension on the tensioning/supporting cable.
The flex sections of the primary ducting are connected to the rigid sections (so-called hard bodied sections) by flexible couplers secured by a pair of annular clamps. One end of the flexible coupler is mounted to the hard body section by a clamp having double annular bead receiving grooves or channels each tensionable by its own latch. By partially releasing one of the latches, for example the latch adjacent to the hard body section, the flexible section is still held securely by the flexible coupler, but the hard body section may be rotated about its longitudinal axis relative to the flexible coupler and then re-clamped into its desired orientation.
A frusto-conical diffuser is mounted to the inclined base of the diffuser fitting and secured by a double bead receiving clamp. The inclined base is mounted over an aperture in the hard body section. A section of secondary hose is mounted to the diffuser by another flexible coupler. A vacuum head may be secured at the anterior end of the secondary hose by a connector such as another flexible connector or coupler.
The removable thirty degree base of the diffuser fitting has a rigid base flange having a resilient under-gasket in contact with the hard body section. It is secured to the hard body section by a clamp passing around the hard body section. Upstream of the aperture in the hard body section is a locking member while downstream is an upstanding gusset, which is aligned with a corresponding slot in base flange of the fitting. The gusset has an aperture, which will accept a clip to retain the fitting snugly in place. The gusset prohibits rotation of the fitting on the hard body section during closure of retaining clamp. The retaining clip also has a ground wire to eliminate static electricity build-up.
The helically wrapped wire in the large diameter flex hose of the flexible section of the primary ducting is exposed near the hard body section. Static electricity build up may be eliminated by bringing the wire in contact with the clamp on the hard body section or by clipping a ground wire to it.
A length of flexible cable joins each hard body section, and is connected between rigid connection bars secured to the inner surface near each of the ends. The cables prohibit over-extension of each flexible section along the vacuum manifold provided by the primary ducting.
For use in localized general ventilation and localized exhaust ventilation, the vacuum conduit system for removal of fumes and air borne particulate matter according to the present invention may be summarized as including a primary duct and a plurality of flexible secondary ducts mounted in fluid cooperation to the primary duct. The primary duct includes hollow rigid conduit sections interspersed between, and in fluid communication with, hollow flexible conduit sections. An upstream end of the primary duct is sealed substantially air-tight. An opposite downstream end of the primary duct cooperates with an air extraction means for extracting air from the primary duct so that the primary duct functions as a vacuum manifold. Secondary ducts may be mounted at their downstream ends to the rigid conduit sections and inclined at an inclined angle relative to the rigid conduit sections so that secondary airflows leaving the downstream ends of the secondary ducts are inclined into an airflow stream in the primary duct so as to be directed in a downstream direction of the airflow stream in the primary duct. It is an object to generally equalize vacuum levels at the downstream ends of the secondary ducts.
The secondary ducts may be short fittings or just localized capture apertures for localized general ventilation, or may include long flexible hoses for localized exhaust ventilation. The primary duct has a constant first diameter and the secondary duct has a second diameter. The first and second diameters preferably form a ratio of greater than two. The ratio may be 16:6 or 16:4, or may be in the range of 16:4 to 16:6. The inclined angle may be substantially thirty degrees.
The rigid section may be cylindrical and the secondary duct may be mounted thereto by means of a generally cylindrical diffuser fitting inclined at the inclined angle in the downstream direction of the airflow stream in the primary duct. The diffuser fitting has a downstream aperture and the rigid section has an aperture in a wall thereof, so that the downstream aperture of the diffuser fitting mates and seals over the aperture in the wall of the rigid section. The diffuser fitting may include a conical frustum mounted at a narrow end thereof to the downstream end of the secondary duct. A cylindrical section of the fitting is mounted to the wider opposite end of the conical frustum. The aperture in the wall of the rigid section may be pyriform so as to have a narrower end and an opposite broader end, wherein the narrower end is upstream of the broader end along the airflow stream in the primary duct. The rigid section may include a rotatable section selectively rotatably mounted by cuff mounting means between adjacent flexible sections so as to be selectively rotatable about a longitudinal axis of the airflow stream in the primary duct. Selectively releasable locking means may be provided for locking the rotatable section on the cuff mounting means relative to the flexible sections in an angular position so as to generally direct a corresponding secondary duct of the plurality of secondary ducts to a desired workspace.
The primary duct may include sections of flexible tube as the flexible conduit sections. Each secondary duct of the plurality of secondary ducts may be a flexible hose. A vacuum head may be mounted at the upstream-most end of each of the secondary ducts. A cable suspension means may be provided for suspending the primary duct under a cable of the cable suspension means, wherein the cable is mountable, and releasably tensionable by tensioning means, between rigid supporting surfaces.